The subject matter of this application is related to that of copending and Commonly Owned U.S. patent application Ser. No. 819,397, filed January 17, 1986, in the names of Marc S. Newkirk, et al. and entitled "Composite Ceramic Articles and Methods of Making Same". This co-pending application discloses a novel method for producing a self-supporting ceramic composite by growing an oxidation reaction product from a parent metal into a permeable mass of filler. The resulting composite, however, has no defined or predetermined configuration.
The method of growing a ceramic product by an oxidation reaction is disclosed generically in U.S. Pat. No. 4,713,360 which issued on December 15, 1987 and was based on Commonly Owned U.S. patent application Ser. No. 818,943, filed January 15, 1986, in the names of Marc S. Newkirk, et al. and entitled "Novel Ceramic Materials and Methods of Making the Same". This patent discloses the method of producing self-supporting ceramic bodies grown as the oxidation reaction product from a parent metal as the precursor. Molten parent metal is reacted with a vapor-phase oxidant to form an oxidation reaction product, and the metal migrates through the oxidation reaction product toward the oxidant thereby continuously developing a polycrystalline ceramic body of the oxidation reaction product. Typically in the polycrystalline ceramic bodies, the oxidation reaction product crystallites are interconnected in more than one dimension, preferably in three dimensions. When the process is not conducted beyond the exhaustion of the parent metal, the ceramic body obtained is dense and essentially void free. Where desired, the ceramic body can be produced having metallic components and/or porosity, which may or may not be interconnected. The process may be enhanced by the use of an alloyed dopant, such as in the case of an aluminum parent metal oxidized in air. This method was improved upon by the use of external dopants applied to the surface of the precursor metal as disclosed in copending and Commonly Owned U.S. patent application Ser. No. 822,999, filed January 27, 1986, in the names of Marc S. Newkirk, et al. and entitled "Methods of Making Self-Supporting Ceramic Materials".
Further developments of the foregoing methods enable the formation of ceramic composite structures comprising a polycrystalline ceramic matrix embedding a filler and having one or more cavities formed by inversely replicating the geometry of a shaped, precursor parent metal. These methods are described in (1) Commonly Owned U.S. patent application Ser. No. 823,542, filed January 27, 1986, in the name of Marc S. Newkirk, et al., and entitled "Inverse Shape Replication Method of Making Ceramic Composite Articles and Articles Obtained Thereby", and (2) Commonly Owned U.S. patent application Ser. No. 896,157, filed August 13, 1986 in the name of Marc S. Newkirk and entitled "Method of Making Ceramic Composite Articles with Shape Replicated Surfaces and Articles Obtained Thereby".
Also, a method was developed for making ceramic composite structures having a pre-selected shape or geometry by utilizing a shaped preform of permeable filler into which the ceramic matrix is grown upon the bulk oxidation of a parent metal, as described in Commonly Owned U.S. patent application Ser. No. 861,025, filed May 8, 1986, in the names of Marc S. Newkirk et al. and entitled "Shaped Ceramic Composites and Methods of Making the Same".
Shaped ceramic composites exhibiting high fidelity have been achieved by utilizing a barrier means to arrest or inhibit the growth of the oxidation reaction product at a selected boundary to define the shape or geometry of the ceramic composite structure. This technique is described in Commonly Owned U.S. patent application Ser. No. 861,024, filed May 8, 1986, in the names of Newkirk et al. and entitled "Method of Making Shaped Ceramic Composites with the Use of a Barrier".
The entire disclosures of all of the foregoing Commonly Owned U.S. Patent Applications Patent are expressly incorporated herein by reference.
One factor in using the methods of the above-mentioned Commonly Owned U.S. Patent Applications to produce a ceramic composite body is that the filler materials employed are permeable to the oxidant when required for the oxidant to contact the molten parent metal and further are permeable to infiltration by the developing oxidation reaction product into the filler. The ceramic composite structures produced are generally an integral, unitary ceramic composite body which may have the original configuration of a preform of filler, or may include a cavity whose boundaries and geometry are determined by the shape of a preshaped parent metal.
The present invention is a still further improvement in providing a self-supporting ceramic body having spaced wall members each with a bounded cross-section defining fluid passageways, which ceramic body is produced by inverse replication of a shaped parent metal.